Engines mounted in an engine compartment of a vehicle or the like include an engine of natural intake mode in which air is taken in due to a differential pressure between the inside and the outside of a combustion chamber, and an engine of supercharger mode in which air is fed under pressure into a combustion chamber by a supercharger.
Such engines, as described above, are provided with auxiliary equipment such as a water pump, an intake system structure such as an air cleaner, and an exhaust system structure such as an exhaust manifold. A radiator, a battery and the like are also mounted in the engine compartment. However, in recent vehicles, since additional apparatuses such as an air conditioner, a power steering unit and the like are mounted thereon, the space in all directions in the engine compartment is narrow. Further, in recent engines, the intake system structures tend to be large-sized in view of problems of output, fuel cost, emissions or the like.
In such an engine as described above, in the case where an intake system structure such as an air cleaner is mounted, interferes with the vehicle body when the latter is mounted in the engine compartment. Therefore, it is necessary to mount the intake system structure after the engine is mounted on the vehicle body, resulting in an inconvenient mounting or assembling process.
Further, in the case where the intake system structures are mounted on the engine after the latter has been mounted in the engine compartment, they cannot be mounted close to each other from a viewpoint of space relative to other auxiliary equipment and apparatuses, resulting in an inconvenience of lowering the external appearance of the engine.
Furthermore, on some engines or even the same engine, the intake system structures are changed into a natural intake mode or a supercharger mode. In such an engine, in order to mount the intake system structures that are different in mode, it is necessary to provide one mounting bracket for the natural intake mode and another mounting bracket for the supercharger mode, resulting in an inconvenience and increasing cost.